"This is a much-needed testament and historical document from one of the great environmentalists of our time.” —Edward O. Wilson, University Research Professor, Harvard University, on Lester Brown's memoir Breaking New Ground.

The term hydropower has traditionally referred to dams that harnessed the energy in river flows, but today it also includes harnessing the energy in tides and waves as well as using smaller “in-stream” turbines to capture the energy in rivers and tides without building dams. 99

Roughly 16 percent of the world’s electricity comes from hydropower, most of it from large dams. Some countries such as Brazil and the Democratic Republic of the Congo get the bulk of their electricity from river power. Large dam building flourished during the third quarter of the last century, but then slowed as the remaining good sites for dam building dwindled and as the costs of displacing people, ecological damage, and land inundation became more visible. 100

Small-scale projects, which are not nearly as disruptive, are still in favor. In 2006, small dams with a combined 6,000 megawatts of generating capacity were built in rural areas of China. For many rural communities these are currently the only source of electricity. Though China leads in new construction, many other countries are also building small-scale structures, as the economics of generation increasingly favor renewable sources over fossil fuels. And there is growing interest in in-stream turbines that do not need a dam and are less environmentally intrusive. 101

Tidal power (actually, lunar power) holds a certain fascination because of its sheer potential scale. Canada’s Bay of Fundy, for example, has a potential generating capacity of more than 4,000 megawatts. Other countries are looking at possible projects in the 7,000- to 15,000-megawatt range. 102

The first large tidal generating facility—La Rance barrage, with a maximum generating capacity of 240 megawatts—was built 40 years ago in France and is still operating today. Within the last few years interest in tidal power has spread rapidly. South Korea, for example, is building a 254-megawatt project on its west coast. Scheduled for completion in 2009, this facility will provide enough electricity for the half-million people living in the nearby city of Ansan. At another site 30 miles to the north, engineers are planning an 812-megawatt tidal facility near Incheon. In March 2008, Lunar Energy of the United Kingdom reached agreement with Korea Midland Power to develop a turbine field off the coast of South Korea that would generate 300 megawatts of power. China is planning a 300-megawatt tidal facility at the mouth of the Yalu River near North Korea. Far to the south, New Zealand is planning a 200-megawatt project in the Kaipara Harbour on the country’s northwest coast. 103

Giant projects are under consideration in several countries, including India, Russia, and the United Kingdom. India is planning to build a 39-mile barrage across the Gulf of Khambhat on the country’s northwest coast with a 7,000-megawatt generating capacity. In the United Kingdom, several political leaders are pushing for an 8,600-megawatt tidal facility in the Severn Estuary on the country’s southwest coast. This is equal to 11 percent of U.K. electrical generating capacity. Russian planners are talking in terms of a 15,000-megawatt tidal barrage in the White Sea in northwestern Russia, near Finland. Part of this power would likely be exported to Europe. A facility under discussion for Tugurski Bay on the country’s Far Eastern coast would provide 8,000 megawatts to power local industry. 104

In the United States, the focus is on smaller tidal facilities. Since 2007 the Federal Energy Regulatory Commission has issued more than 30 preliminary permits, including those for projects in Puget Sound, San Francisco Bay, and New York’s East River. The San Francisco Bay project by Oceana Energy Company will have at least 20 megawatts of generating capacity. 105

Wave power, though it is a few years behind tidal power, is now attracting the attention of both engineers and investors. In the United States, the northern Californian utility PG&E has filed a plan to develop a 40-megawatt wave farm off the state’s north coast. GreenWave Energy Solutions has been issued preliminary permits for two projects of up to 100 megawatts each off California’s coast, one in the north and one in the south. And San Francisco is seeking a permit to develop a 10–30 megawatt wave power project off its coast. 106

The world’s first wave farm, a 2-megawatt facility built by Pelamis Wave Power of the United Kingdom, is operating off the coast of Portugal. The project’s second phase would expand this to 22 megawatts. Scottish firms Aquamarine Power and Airtricity are teaming up to build 1,000 megawatts of wave and tidal power off the coast of Ireland and the United Kingdom. Ireland as a whole has the most ambitious wave power development goal, planning 500 megawatts of wave generating capacity by 2020, enough to supply 7 percent of its electricity. Worldwide, the harnessing of wave power could generate a staggering 10,000 gigawatts of electricity, more than double current world electricity generation of 4,000 gigawatts from all sources. 107

We project that the 945 gigawatts (945,000 megawatts) of hydroelectric power in operation worldwide in 2008 will expand to 1,350 gigawatts by 2020. According to China’s official projections, 270 gigawatts will be added there, mostly from large dams in the country’s southwest. The remaining 135 gigawatts in our projected growth of hydropower would come from a scattering of large dams still being built in countries like Brazil and Turkey, a large number of small hydro facilities, a fast-growing number of tidal projects, and numerous smaller wave power projects. 108

Within the United States, where there is little interest in new dams, there is a resurgence of interest in installing generating facilities in non-powered dams and in expanding existing hydro facilities. If the worldwide interest in tidal and wave energy continues to escalate, the additional capacity from hydro, tidal, and wave power by 2020 could easily exceed the 400 gigawatts needed to reach the Plan B goal. 109